Major Set Symbol Cleanup

This major point release includes a number of set symbol corrections after comparing the Keyrune version with high resolution card scans. Updates were made to 4th Edition through 8th Edition, Mirage, Visions, Portal 2, and Shadowmoor. The original Ice Age logo was added as an alternate version.

There are also new icons for unofficial "sets" or compilations, including Collector's Edition, International Collector's Edition, APAC Lands, Euro Lands, Two Player Introductory Set, and Alternate 4th Edition.

Finally the documentation site got a cool new update with "icon previews": clicking a symbol on the Icons page will show a large preview with some functions, and you can link directly to icons on that page. More to come in the readme.